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Painting a BJ8 Radiator - any advice?

Last year, I stripped the radiator of my BJ8 down to bare metal (brass tanks) and then painted it using Dupli-Color Engine enamel. Last week, a significant crack in the paint appeared, and then pieces (size of a quarter) came cleanly off, exposing the clean brass below. Clearly, the paint did not adequately adhere, despite my having taken great pains to strip and then thoroughly clean the surface before painting.

Had anyone had success painting their rad? What prep and products did you use?

I looked at Radiator Paint on the Eastwood site and asked about prep. They recommended a ‘misting of self-etching primer first’, however the product spec for self-etching primer states that it is only stable to 170F....

Re: Painting a BJ8 Radiator - any advice?

Hi Steve,

Before I would have painted the tank, I would have applied a primer to get grater adherence to the cleaned metal. Also, CaptRandy had a good question, as if stripper sediment is not eliminated, it could cause those areas not to adhere to the metal. At this point, I would remove the present coating, wash the clean metal with water and allow to thoroughly dry, apply a primer and then apply the finishing coats.

Yes, a great deal of work but I expect it will last longer then your present application.

Re: Painting a BJ8 Radiator - any advice?

Hi, the entire top of the tank was stripped with a methylene chloride paint stripper, then cleaned with Varsol then acetone. I roughed the metal up with 1000 grit before a final wipe down with acetone followed by compressed air. Only half of the top tank has had paint loss.

Re: Painting a BJ8 Radiator - any advice?

I think a primer is a good idea, but I can’t seem to find one that tolerates higher temperatures. I’d particularly like to use a primer that someone in this forum has used successfully rather than just find one on the Internet....

Re: Painting a BJ8 Radiator - any advice?

prep cleaned brass tank , sanding with 600 is better, use PPG DX 330 wax and grease remover,( Usually after I chemically strip tank I wash with warm water, scrub the crap out of it with scotch brite pads and tooth brush in crevises)
then after compressed air drying , tack down and I use PPG DP epoxy primer(black) thinned out as a sealer, ( its really thin ,you do not want too much material such as a sanding primer or etching primer, this stuff sticks to glass ! )
then I use PPG DCC 9300 ( black) with flattening agent to make it just under semi gloss , at this point you can also use your spray can of choice. The DP epoxy is what does the trick for adhesion. FOr the core part If radiator is out of car I would just use a spray can and keep it thin . The top is seen and regularly cleaned. If you do it right you cannot notice any color or sheen differences between the two and urethane will provide some protection paintwise to some abuse. Bottom of tank same way top is done. FWIW .

Re: Painting a BJ8 Radiator - any advice?

I painted the rad in the spring of 2018 and the finish was fine until 3 weeks ago when we hit a major cold snap. The car resides in my garage, which is attached to the house, but it was probably subjected to temperatures as low as -15F.

Re: Painting a BJ8 Radiator - any advice?

Just a thought...brass sheet metal expands /contracts with heating/cooling...just wondering if the engine paint you used is made to flex that much? There are paints (in spray cans) specifically for automotive radiators.

Re: Painting a BJ8 Radiator - any advice?

Hi Steve,

In your first attempt, I think you did a job more appropriate for painting a fender. However, as you have indicated, the radiator does expand and contract so the paint needs something more to grab and your 1000 grit sanding made the surface to smooth to provide sufficient grip. I agree with Steveg as the radiator gets hot but within the limits of standard

Rustoleum or Krylon spray paints (I used a satin black Rustoleum last painted around 15 years ago). I roughed up the tanks with a medium grit paper for the primer to grab. The primer filled in any roughness and provided a good adhesive surface for the final paint to grip.

Considering the red fan guard originally had brush marks in the paint from the factory, I would suggest you not overdo the finish on the tank.